Snowball fights are a classic snow day activity. At your advanced age, though, you can take things to the next level. Use what you learned in your engineering classes to make the most impenetrable snow fort or your physics knowledge to determine the optimal angle and force with which to throw your snowball to best hit your target.
If your campus features large hills, there's no better way to spend the day then sledding down them. In the small dorm rooms, though, you'll have a hard time finding space to store a proper sled. This is where the cafeteria comes in. Grab one of the food trays and use it to go "traying" down the hills.
Snow men are so passe. Any kid can roll a few balls of snow and stick a carrot in the mouth. Put your studio art classes to work by creating snow sculptures. Start by gathering a big block of snow, then use your sculpture tools to carve it. If others are interested, you could have a themed contest to see who can design the best sculpture.
If you're not into the frightful weather outside, you can cuddle up inside where the fire (or the heater) is so delightful. Call up a few friends and gather in the dorm common room for a movie or TV marathon. You could watch all of the movies or episodes in a series back-to-back or you could pick another theme, like alien movies or movies that star a favorite actor. Bring along some snacks to share.